A spurious regression refers to a situation where:. a. the direction of the relationship between the dependent variable and the explanatory variables is uncertain.
b. even though two variables are independent, the OLS regression of one variable on the other indicates a relationship between them.
c. a few important and necessary explanatory variables are left out of a regression equation, thus leading to inefficient and inconsistent forecasts.
d. at least one of the variables used in a regression equation does not have a unit root and the error terms are heteroskedastic.

b. even though two variables are independent, the OLS regression of one variable on the other indicates a relationship between them.

Explanation:

An experiment can be defined as an investigation which typically involves the process of manipulating an independent variable (the cause) in order to be able to determine or measure the dependent variable (the effect).

This ultimately implies that, an experiment can be used by scientists to show or demonstrate how a condition causes or gives rise to another i.e cause and effect, influence, behavior, etc in a sample.

In an experiment , the variable being manipulated by an experimenter is known as an independent variable while the dependent variable is the event expected to change when the independent variable is manipulated

A spurious regression refers to a situation where even though two (2) variables are independent, the ordinary least squares (OLS) regression of one independent variable on the other variable indicates a relationship between them.

An ordinary least squares (OLS) regression is typically designed to be used in estimating unknown variables or parameters in a linear regression model.